Hydrogen’s stock is rising in terms of its perceived value in longer-term efforts to transform the environmental sustainability of aviation. It also seems to have the potential of unlocking significantly greater payload and range than seems likely to be delivered by electric batteries for the foreseeable future.
Nevertheless, many people in the aviation sector still don’t completely grasp how all the dots join up when it comes to making hydrogen a mainstream fuel source. A new report from research intelligence group PreScouter called Hydrogen-based Energy Adoption in Aviation makes a good attempt at demystifying the subject.
The report provides an easy-to-follow snapshot of what PreScouter calls the Hydrogen Energy Value Chain. This breaks down the tasks and assets involved in the generation, transportation, and storage of hydrogen that need to be in place to make it a viable alternative to fossil fuel.
It also breaks down what the authors see as the anticipated timeline for aviation’s adoption of hydrogen over the next three decades. In the short term, through 2025, they see preparatory steps such as the replacement of airport ground support equipment with hydrogen-powered units.
Over the medium term (2026-2035), the authors believe, new synthetic jet fuels will start to be used on aircraft in ways that do not require changes to existing infrastructure. The report offers a useful comparison between the characteristics of so-called synfuel and more advanced hydrogen applications, including fuel cells and direct consumption by turbine engines.
The PreScouter team envisages that the more widespread adoption of hydrogen won't happen until the 2036-2050 timeframe. They expect this to entail significant redesign to aircraft architecture, propulsion systems, and supporting infrastructure.
The measured analysis of the potential for hydrogen use in aviation concludes with an assessment of potential roadblocks. These include challenges for aircraft design, infrastructure, and the regulatory environment.
"A large-scale switch to hydrogen propulsion is expected to be available between 2035 and 2050," PreScouter technical director Sofiane Boukhalfa told FutureFlight. "The International Energy Agency has said we can expect to see green hydrogen capacity of 40 gigawatts in Europe by 2030."
However, he pointed out that this depends on further advances in renewable energy production using methods such as wind or solar power. "Without such growth, the aviation industry might have to feed its new ecological aircraft with grey hydrogen, produced using natural gas and thus producing carbon dioxide," Boukhalfa stated.
"The quickest path [to producing so-called green hydrogen] will likely be to create hydrogen from water through electrolysis using renewable energy sources like solar or wind power," he explained to FutureFlight. "Once produced, hydrogen can be used in much the same way as natural gas, with the only emissions being water vapor and not the carbons that are harmful to the planet."
Multiple projects are underway to explore and develop the potential for hydrogen to be produced in other ways. These include, for example, using microbes that use light to make hydrogen and converting biomass into gas or liquids, and then separating the hydrogen. According to PreScouter, the latest estimates show that direct combustion of hydrogen by turbine engines would reduce the climate impact of flights by around 50 to 75 percent, rising to 75 to 90 percent for propulsion based on hydrogen fuel cells.
One other benefit of a switch to hydrogen is that its supply is generally less susceptible than oil to political tensions and conflict in some parts of the world. However, for now, due to limited production capacity, it remains a comparatively expensive fuel source.
According to the Hydrogen Council, current production costs for green hydrogen are between €3 to €7 per kilogram, compared with €1.50 for grey hydrogen and €0.50 for kerosene (i.e., jet-A fuel). PreScouter estimates that the cost could be cut in half over the next three to five years. This will require significant investment in production infrastructure—perhaps as much as $20 billion to close the gap with grey hydrogen.